Symptoms

• Symptoms on foliage

In growing crops, the symptoms appear after long periods of rain and are characterised by a whitish mould on the lower part of the stems and at the leaf axils. The tissues are gradually destroyed and the diseased stems fold, wilt and fade (photos 1 to 5), and finally, in the case of early and severe soil infestation, the plants may die.

In favourable conditions, e.g. when humidity is high, large black sclerotia can be observed on the diseased tissues or inside the stems (photos 6 to 8).

• Symptom on tubers

In wounded tubers, the symptoms of rot at the heel-end which are quite rare, are caused mainly by S. minor. Typical sclerotia are visible in the affected tissues (photo 9).